Hi all:
There seems to be a lot of stress/load testing tool that support AJAX. I am wondering how well does these tool implemented. Do they only record http request and replay it? Is it the right way to test AJAX app? How does google test their ajax apps? Any suggestion welcome!
Google apps are written in GWT, which comes with its own extension to JUnit. Article on unit testing ajax applications with GWT.
I've used SilkPerformer at a previous job. According to the link, they have some AJAX enhancements. Unfortunately, Silk is far from free.
All load testers would support AJAX- they're just additional http connections.
There are a few free ones out there- Jmeter, BadBoy, Grinder that all do it well.
All of them have some sort of support for recording/playback, but that's not always what you're looking for.
Easiest way I've done it is to record a sample session, replace a few params with variables and loop it off of a csv or excel file.
Great starting point: video of a google presentation on open source testing.
If you don't want to setup your own load testing server there are a couple of free online load testing services that can run load tests directly over the Internet. For example http://loadimpact.com or http://loadstorm.com
Check out Jiffy. It's an end-to-end measurement suite, and is subsequently kind of complex. However, the statistics are quite impressive.
I've used Virtual User Generator, which is a part of the Loadrunner software from HP, to test AJAX applications. The software has several application protocols that can be used to record web applications, e.g. AJAX, and Click and Script.
For the majority of web application load testing it is sufficient to record and replay http requests. This will give the result of how the servers are handling the load. If your web application does a lot of asynchronous loading, and rendering on the client side, e.g. parsing large datasets of xml or json, or many DOM modifications, it can be relevant to include the browser tier to measure the end user experience.
Most of the load testing tools out there do AJAX load testing the same way: they execute the raw HTTP traffic that is seen during a "recording" phase (which can be page requests, image requests, or even AJAX requests). The main difference among them is how good their recorder/IDE tool is and how easily it helps you parameterize the HTTP requests such that they reflect real world traffic based on dynamic/realtime results.
Warning, blatant plug: The only real exception to this is my company, BrowserMob. Instead of simulating the traffic observed, it actually uses real web browsers to drive back load. As such, the AJAX stuff is handled by the browser.
Useful link: Separate from the blatant plug above (though I do hope you check it out - we're up front with the pricing and provide a free trial), I recently wrote an article for Ajaxian about AJAX load testing. It goes in to more detail about the technical implications of using real browser users (RBUs) vs. virtual users (VUs).
You can also have a look at fwptt it is open source. If you are a .net developer you can make use of the parameter automatic handling and the possibility to use your own .net object for doing the tests.